Alloy for pen points



United States Patent 3,480,429 ALLOY FOR PEN POINTS Maria T hiede, neeMentzner, and Konrad Ruthardt, Hanan am Main, Germany, assignors to W.C. Heraeus G.m.b.H., Hanan am Main, Germany, a corporation of Germany NoDrawing. Continuation of application Ser. No. 560,883, June 27, 1966.This application Jan. 23, 1969, Ser. No. 796,296

Int. Cl. C22c 5/00 US. Cl. 75134 5 Claims ABSTRACT OF THE DISCLOSURE Analloy suitable for use in the casting of pen points having up to 50weight percent of osmium and/or rhenium, 30 to 45 weight percentiridium, 5 to 20 weight percent ruthenium, up to 25 weight percent of anoble metal, and up to weight percent of la base metal of Group 8, suchas cobalt.

This is a continuation of application Ser. No. 560,883, field June 27,1966, now abandoned, which in turn was a continuation-in-part ofapplication Ser. No. 543,515, filed April 19, 1966, now abandoned.

The present invention relates to an alloy which is especially suitablefor producing the tips of pen points.

For this purpose it has been conventional prior to this invention toemploy especially alloys which have a high content of osmium orruthenium aside from other metals of the platinum group and which asalloying constituents also contain varying amounts of base metals,especially tungsten.

Among these alloys, especially those which contain a high percentage ofosmium were always preferred for making the tips of :pen points becauseof their particular property of having a high abrasive resistance.However, apart from the high melting point of such osmium alloys whichrenders the production of well-formed spherical tips for pen points verydiflicult, they have the further disadvantage of being extremelyexpensive. Consequently, most consumers prefer to use pen points withtips which are made of cheaper alloys, even though they possess thedisadvantages of these materials rather than using pen points the tipsof which are made of materials with a high osmium content which have avery high abrasive resistance but are very expensive.

According to the present invention, the surprising discovery has nowbeen made that it is also possible to make the tips of pen points ofmaterials with a lower osmium content which despite their considerablylower cost are equivalent to alloys with a high osmium content, even ifthe osmium is completely replaced by another metal, namely, rhenium.This result was especially surprising because it was also found that thealloys according to the invention also possess all the other propertieswhich are important in materials for producing the tips of pen points.

The new alloys comprise according to the present invention of up to 50%,preferably 25 to 40%, of osmium, of to 50%, preferably 30 to 45% ofiridium, and 5 to 20%, preferably more than 8%, of ruthenium, whichalloys are made in the conventional manner of producing alloys for use'as the tips of pen :points. The osmium content may be re laced partlyor entirely by rhenium. These alloys further contain, other than asmentioned, precious metals of the 8th group of the periodic system,namely, platinum, palladium, and/or rhodium. The content of these alloyconstituents when employed together should, however, not exceed whilethe content in platinum ice or palladium alone may amount up to 15% ofthe entire alloy. The content in rhodium, however, should generally onlyamount up to 10%. Apart from these precious metals, the alloys accordingto the invention also contain base metals of the 8th group of theperiodic system, that is, either individually or together up to 15%. Onevery useful addition has been found to consist of cobalt.

The most important property of these alloys is their high abrasiveresistance which can otherwise be attained only by alloys with a highpercentage of osmium or by the natural osmi-iridium. As compared withthese materials which are known for making the tips of pen points, thealloys according to the invention have, however, the considerableadvantage of having much lower melting points and of therefore beingeasily melted, and of also permitting the production of well-shapedspherical tips to be carried out without difliculty. In addition, thenew materials have a high compressive strength, a high tenacity, and afine-grained structure free of pores. The tips which are made of thesealloys may be easily welded upon the pen points and, since they may beeasily polished, they permit very soft and delicate writing. Their inkresistance fully complies with all requirements even if the osmium isreplaced completely by rhenium.

The alloys according to the invention may have, for example, thefollowing composition:

Example 1: 25% Os; 35% Ir; 13% Ru, 10% Pt; 1% Rh;

12% Re; and 4% Co.

Example 2: 35% 0s; 40% Ir; 10% Ru; 9% Pt; 3% Rh;

and 3% Co. Example 3: 30% Re; 5% Os; 38% Ir; 12% Ru; 9% Pt;

1% Rh; and 5% Co.

Example 4: 38% Re; 36% Ir; 10% Ru; 10% Pt; 1% Rh;

and 5% Co.

Having thus fully disclosed our invention, what we claim is:

1. An alloy useful in the production of ball point pen tips consistingessentially of 25 to 40 weight percent of at least one metal selectedfrom the group consisting of osmium and rhenium, 30 to 45 weight percentiridium, 8 to 20 weight percent ruthenium, 10 to 25 weight percent of atleast one noble metal selected from the group consisting of platinum,palladium and rhodium, and 3 to 15 weight percent of a base metal of theV111 group of the periodic table.

2. An alloy as claimed in claim 1, having the following composition: 25%osmium, 35% iridium, 13% ruthenium, 10% platinum, 1% rhodium, 12%rhenium, and 4% cobalt.

3. An alloy as claimed in claim 1, having the following composition: 35%osmium, 40% iridium, 10% ruthenium, 9% platinum, 3% rhodium, and 3%cobalt.

4. An alloy as claimed in claim 1, having the following composition: 30%rhenium, 5% osmium, 38% iridium, 12% ruthenium, 9% platinum, 1% rhodium,and 5% cobalt.

5. An alloy as claimed in claim 1, having the following composition: 38%rhenium, 36% iridium, 10% ruthenium, 10% platinum, 1% rhodium; and 5%cobalt.

References Cited UNITED STATES PATENTS 1/1932 Ledig -172 6/1937 Powellet al. 75-172 U.S. C1.X.R.

